Method of using an electron capture type detector

Abstract

An electron capture type detector for gas chromatography has an ionization vessel containing therein line sources for a radioactive isotope serving as a negative electrode, a collector electrode, a purge gas route, a discharge gas route, and an end of a column disposed at its lower section. The collector electrode includes a filament made of a heat resistant material and itself connected to a heating device such that the filament can be heated to about 300°-600° C. so as to eliminate contaminants deposited on the collector electrode by thermal decomposition, oxidation or reduction, without the necessity of disassembling the detector itself. The contaminants are effectively removed by simultaneously causing air or hydrogen gas to pass over the collector electrode through the ionization vessel from the purge gas route to the discharge gas route.

What is claimed is: 
     
       1. A method of operating an electron capture type detector, said detector comprising an ionization vessel having therein line sources for a radioactive isotope serving as a negative electrode, a collector electrode, a purge gas route and a discharge gas route, and having an end of a column disposed at a lower section of said ionization vessel, said method comprising the steps of: heating said collector electrode, for removing contaminants from said collector electrode, by causing an electric current to flow through a filament which is connected to a heating means and of which said collector electrode is comprised; and   simultaneously causing air or hydrogen gas to pass through said ionization vessel from said purge gas route to said discharge gas route over said collector electrode.   
     
     
       2. The method of claim 1 wherein said filament is heated to a temperature in the range of about 300°-600° C.